Silicon-containing materials with controllable microstructure

ABSTRACT

In various embodiments, provided are silicon-containing coatings; silicon-containing coatings comprising microstructures that are responsive to one or more stimuli; oxidized products of said silicon-containing coatings; bulk solids; oxidized solids and powders; methods of preparing such coatings, solids, and powders; and substrates comprising the provided coatings.

TECHNICAL FIELD

The present application relates to silicon-containing coatings;silicon-containing coatings comprising stimuli-responsivemicrostructures; oxidized products of such silicon-containing coatings;oxidized solids and powders; methods of preparing said coatings, solids,and powders; and substrates comprising the provided coatings.

BACKGROUND

Silicon based sol-gel coatings have received considerable researchbecause of their advantages in chemical and thermal stability coupledwith their ability to be processed as low viscosity liquids. Sol-gelprocesses have been combined with organic compounds such as surfactantsor block copolymers, which act as sacrificial templates in the formationof porous inorganic materials when the organic materials are selectivelyremoved by thermal or chemical means. To change the microstructure ofthe sol-gel based coatings, typically a different formulation containingeither different amounts of the organic template or an altogetherdifferent organic additive is required.

Some known polymer coatings can respond to stimuli such as moisture orpH. Such materials may be useful for providing a mechanical response toa change in the environment for diverse applications, including sensorsand active coatings. Although various methods of depositing sol-gelcoatings are known, and various methods of producing stimuli-responsivemicrostructured polymer films are known, there remains a need in the artfor cost-effective methods of creating silicon-based coatings.Additionally, there is need for methods and materials that allow themicrostructure of such silicon-based coatings to be controlled byexposure to at least one stimulus. Moreover, there is need for coatingshaving a fine pore structure, wherein preparation of such coatings canbe achieved without additives such as surfactants and block copolymers.

SUMMARY

These needs are met by the described embodiments, which providesilicon-containing coatings, solids, and powders; methods of formingsuch materials; and substrates comprising the provided coatings.

In various embodiments, the provided methods comprise: (I) reacting anamine-reactive compound having at least one free-radical polymerizablegroup per molecule with a silane having the formula:

(R¹ ₂NR²)_(a)SiR³ _(b)(OR⁴)_(4-(a+b))

wherein a=1, 2, or 3; b=0, 1, 2, or 3; a+b=1, 2, 3, or 4; R1 isindependently selected from hydrogen, C1-C12 alkyl, halogen-substitutedC1-C12 alkyl, C1-C12 cycloalkyl, aryl, nitrogen-substituted C1-C12alkyl, and aliphatic ring structures which bridge both R¹ units and canbe N-substituted; R² is independently selected from C1-C30 alkyl; R³ isindependently selected from hydrogen, halogen, C1-C12 alkyl,halogen-substituted C1-C12 alkyl, and —OSiR^(3′) ₃, wherein R^(3′) isselected from C1-C12 alkyl, and halogen-substituted C1-C12 alkyl; and R⁴is independently selected from hydrogen, C1-C12 alkyl, andhalogen-substituted C1-C12 alkyl to form a reaction product; wherein thereaction may optionally occur in the presence of at least one optionalsolvent to form a reaction product that is soluble in the at least oneoptional solvent; and (II) reacting the reaction product of (I) with anorganoborane free-radical initiator in the presence of oxygen to form apolymer preparation. The polymer preparation of (II) may be a solid; aliquid; or if the reaction of (I) occurs in the presence of at least oneoptional solvent, a dispersion. The polymer preparation of (II) may beused to prepare one or more of the provided coatings, solids, andpowders.

In some embodiments, the polymer preparation of (II) is treated withheat, acid, or combinations thereof to form an oxidized solid, oxidizedpowder, or both. The oxidized power and oxidized solid may be porous,and in some embodiments, may be microporous or substantiallymicroporous. In alternative embodiments, the polymer preparation of (II)is contacted with at least one substrate surface to form a non-porous orsemi-porous silicon-containing coating on the surface. In someembodiments, said silicon-containing coating comprises microstructuresthat are responsive to one or more stimuli. In some embodiments, theprovided methods further comprise treating the silicon-containingcoating formed with heat, acid, or combinations thereof to form anoxidized coating. The oxidized coating may be porous, and in someembodiments, may be microporous or substantially microporous.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and the many embodimentsthereof will be readily obtained as the same becomes better understoodby reference to the following detailed description when considered inconnection with the accompanying drawings, wherein:

FIG. 1 is a flow chart describing the steps of various embodiments;

FIG. 2 depicts atomic force microscopy (AFM) height images of thesilicon-containing microstructured film prepared in Example 1: images Aand B show the presence of fairly uniform microstructures that areapproximately 7 nm tall and 13 μm diameter; C illustrates that themicrostructures are cylindrical in shape; phase image D showssignificant contrast between the cylinders and the matrix, whereindarker contrast in the image is generally indicative of a softer and/orstickier material;

FIG. 3 depicts AFM (in tapping mode) height images of thesilicon-containing film prepared by heat treating the film prepared inExample 1 for A 2 h/250° C. or for B 2 h/500° C.; C describes themicrostructures of B;

FIG. 4 depicts 3-D AFM images of Examples 4-6: A represents the filmdescribed in Example 4; B represents the film described in Example 5;and C represents the film described in Example 6; wherein the x-axisscale is 10 μm and the z-axis scale is 20 nm in all images;

FIG. 5 depicts AFM images (x-y range 50 nm) of Example 7 films uponindirect exposure to water vapor for A 5 min (ht. z-range 20 nm) and B45 min (ht. z-range 200 nm);

FIG. 6 illustrates fast evolution of microstructure sizes in the filmsof Example 7 (depicted in FIG. 5) as quantified by AFM with time ofindirect exposure to water vapor: A root mean square roughness (RMS) andB cylindrical asperity height; and

FIG. 7 illustrates nitrogen adsorption isotherms for the microporouspowders of Examples 8 and 9, which show Type I behavior (IUPACclassification as defined for example on pp. 12-13 of “Characterizationof Porous Solids and Powders: Surface Area, Pore Size and Density” by S.Lowell et al., Springer, 2004, The Netherlands).

DETAILED DESCRIPTION

Features and advantages of the invention will now be described withoccasional reference to specific embodiments. However, the invention maybe embodied in different forms and should not be construed as limited tothe embodiments set forth herein. Rather, these embodiments are providedso that this disclosure will be thorough and complete and will fullyconvey the scope of the invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention belongs. The terminology used in thedescription herein is for describing particular embodiments only and isnot intended to be limiting. As used in the specification and appendedclaims, the singular forms “a,” “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise.

The term “independently selected from,” as used in the specification andappended claims, is intended to mean that the referenced groups can bethe same, different, or a mixture thereof, unless the context clearlyindicates otherwise. Thus, under this definition, the phrase “X¹, X²,and X³ are independently selected from noble gases” would include thescenario where X¹, X², and X³ are all the same, where X¹, X², and X³ areall different, and where X¹ and X² are the same but X³ is different.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth as used in the specification and claims are to beunderstood as being modified in all instances by the term “about.”Additionally, the disclosure of any ranges in the specification andclaims are to be understood as including the range itself and alsoanything subsumed therein, as well as endpoints. Unless otherwiseindicated, the numerical properties set forth in the specification andclaims are approximations that may vary depending on the desiredproperties sought to be obtained in embodiments of the presentinvention. Notwithstanding that numerical ranges and parameters settingforth the broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical values, however, inherently contain certainerrors necessarily resulting from error found in their respectivemeasurements.

As used herein and the appended claims, the term “coating” is intendedto include, but not be limited to, films.

As used herein and the appended claims, the term “dispersion” isintended to refer to polymer particles dispersed, suspended, dissolved,or partially dissolved in at least one suitable solvent. A dispersionmay be a reaction product, or it may be formed by dispersing a reactionproduct in at least one solvent.

The terms “microstructures” and “microstructured,” as used herein andthe appended claims, are intended to describe materials havingcompositional and/or structural heterogeneities with features having anaverage characteristic length scale of less than 1 mm. When referring toa surface, the terms refer to compositional and or structuralheterogeneities with features having an average characteristic lengthscale of less than 1 mm that are detectable on the surface of a materialby any of the various experimental surface analytical techniques such asatomic force microscopy, scanning electron microscopy, transmissionelectron microscopy, optical microscopy, profilometry, energy dispersivespectroscopy, and x-ray photoelectron spectroscopy. The features ofmaterials with “surface microstructures” or “microstructured surfaces”are distinct from any surface roughness or features of the underlyingsubstrate (or surface) on which the materials are applied.

Unless the context clearly indicates otherwise, the term “porous” isused herein and in the appended claims to mean one or more ofmicroporous (mean pore diameter of less than 2 nm), mesoporous (meanpore diameter of from about 2-50 nm), and macroporous (mean porediameter of greater than 50 nm).

As used herein and the appended claims, the term “powder” is intended tomean granulated particles of a bulk solid.

The terms “solid” and “bulk solid,” as used herein and the appendedclaims, are intended to mean a solid that can be further granulated intoparticles of any size and shape distribution.

In various embodiments, provided are silicon-containing coatings,solids, and powders (collectively, “materials”). In some embodiments,provided are silicon-containing coatings, wherein said coatings may benon-porous or semi-porous and may, in some embodiments, comprisemicrostructures that are responsive to one or more stimuli. In someembodiments, said silicon-containing coatings may be treated to form theprovided porous oxidized coatings. Additionally provided are porousoxidized solids and powders. In addition to the provided coatings,solids, and powders, also provided are methods of preparing suchmaterials. Additionally, substrates comprising the provided coatings arealso provided.

In the various embodiments, provided are methods of preparingsilicon-containing materials, comprising: (I) reacting an amine-reactivecompound having at least one free-radical polymerizable group permolecule with a silane having the formula:

(R¹ ₂NR²)_(a)SiR³ _(b)(OR⁴)^(4-(a+b))

wherein a=1, 2, or 3; b=0, 1, 2, or 3; a+b=1, 2, 3, or 4; R¹ isindependently selected from hydrogen, C1-C12 alkyl, halogen-substitutedC1-C12 alkyl, C1-C12 cycloalkyl, aryl, nitrogen-substituted C1-C12alkyl, and aliphatic ring structures which bridge both R¹ units and canbe N-substituted; R² is independently selected from C1-C30 alkyl; R³ isindependently selected from hydrogen, halogen, C1-C12 alkyl,halogen-substituted C1-C12 alkyl, and —OSiR^(3′) ₃, wherein R^(3′) isselected from C1-C12 alkyl, and halogen-substituted C1-C12 alkyl; and R⁴is independently selected from hydrogen, C1-C12 alkyl, andhalogen-substituted C1-C12 alkyl to form a reaction product; wherein thereaction optionally occurs in the presence of at least one optionalsolvent to form a reaction product that is soluble in the at least oneoptional solvent; and (II) reacting the reaction product of (I) with anorganoborane free-radical initiator in the presence of oxygen to form apolymer preparation. The polymer preparation of (II) may be used toprepare one or more of the provided coatings, solids, and powders. Ifthe reaction of (I) occurs in the presence of an optional solvent, thepolymer preparation of (II) may be a dispersion in which the polymersformed are dispersed, suspended, dissolved, or partially dissolved inthe optional solvent. If the reaction of (I) does not occur in thepresence of an optional solvent, the polymer preparation of (II) may bea liquid or solid. In some embodiments, a dispersion of the liquid orsolid in at least one suitable solvent may need to be prepared in orderto form the provided coatings.

In some embodiments, the provided methods further comprise treating thepolymer preparation of (II) with heat, acid, or combinations thereof toform an oxidized solid, an oxidized powder, or combinations thereof. Theoxidized solids and powders formed may be used in a variety ofapplications. They are also porous, and in some embodiments, aremicroporous or substantially microporous.

In some embodiments, the polymer preparation of (II) is directly treatedwith acid, heat, or both to form an oxidized solid. For example, thepolymer preparation of (II) may be treated with high heat or strongacid. As another example, the polymer preparation of (II) may be treatedwith strong acid and low heat. The oxidized solid formed may begranulated to form an oxidized powder.

In some embodiments, the polymer preparation of (II) is heated toevaporate the solvent of a dispersion polymer preparation or otherwisesolidify a liquid polymer preparation, optionally in the presence of avacuum, to form a bulk solid. The bulk solid can, in some embodiments,be further treated with acid, heat, or both to form an oxidized solid.For example, the bulk solid can be treated with high heat or strongacid. As another example, the bulk solid can be treated with strong acidand low heat. The oxidized solid formed may be granulated to form anoxidized powder.

In some embodiments, the polymer preparation of (II) is heated toevaporate the solvent of a dispersion polymer preparation or otherwisesolidify a liquid polymer preparation, optionally in the presence of avacuum. The bulk solid formed can be granulated to form a powder. Thepowder formed may be further treated with acid, heat, or both to form anoxidized powder. For example, the powder can be treated with high heator strong acid. As another example, the powder can be treated withstrong acid and low heat.

In alternative embodiments, the provided methods comprise contacting atleast one substrate surface with the polymer preparation of (II) and, ifnecessary drying, to form a non-porous or semi-porous silicon-containingcoating. Drying may be achieved through air drying, low heat, vacuum, orcombinations thereof. If the polymer preparation of (II) is a liquid orsolid, it may be necessary to disperse, suspend, dissolve, or partiallydissolve the polymer preparation in at least one suitable solvent inorder to adequately form the coating on the substrate. A suitablesolvent may be, but is not required to be, selected from the at leastone optional solvent of (I). In some embodiments, the coatings formedare films. In some embodiments, the films are stand-alone films preparedon a sacrificial substrate.

The non-porous or semi-porous silicon-containing coatings, as well asthe bulk solid, formed by the provided methods may comprisemicrostructures that are responsive to one or more stimuli. Themicrostructures may, in some embodiments, be protrusions from thecoating or solid surface. In some embodiments, the microstructures mayexist beneath the surface as phase separated domains. In someembodiments, the provided coatings and bulk solids may respond to one ormore stimuli by increasing surface roughness; decreasing surfaceroughness; changing microstructure protrusion size, shape, or both;change of protrusions to lamellar microstructures; change in the size,shape, or both of sub-surface microstructures; or combinations thereof.Examples of stimuli that can illicit a response in the providedsilicon-containing coatings and bulk solids include, but are not limitedto, humidity, pH, and temperature.

In some embodiments, the provided methods further comprise treating thenon-porous or semi-porous silicon-containing coatings with heat, acid,or both to form oxidized coatings. The properties of such oxidizedcoatings are, at least partially, dependent upon the nature of thenon-porous or semi-porous silicon-containing. The oxidized coatingsprepared by the provided methods are porous, and in some embodiments,are microporous or substantially microporous. In some embodiments, theoxidized coatings formed are films. In some embodiments, the films arestand-alone films.

In various embodiments, also provided are the coated substrates preparedaccording to the provided methods. Thus, in some embodiments, providedare coated substrates comprising: (i) at least one silicon-containingcoating on at least one substrate surface; (ii) at least onesilicon-containing on at least one substrate surface wherein the coatingcomprises stimuli-responsive microstructures; (iii) at least oneoxidized coating on at least one substrate surface, or (iv) combinationsthereof.

Amine-Reactive Compounds

The provided methods of preparing silicon-containing materials comprisereacting an amine-reactive compound having at least one free-radicalpolymerizable group per molecule with an amine-functional silane. Theamine-reactive compound may be a small molecule, a monomer, an oligomer,a polymer, or a mixture thereof. The amine-reactive compound may be anorganic, or organopolysiloxane compound. In addition to comprising atleast one free-radical polymerizable group per molecule, the providedamine-reactive compound may also comprise additional functional groups,such one or more hydrolyzable groups.

In some embodiments, amine-reactive compounds may be selected frommineral acids, Lewis acids, carboxylic acids, carboxylic acidderivatives such as anhydrides and succinates, carboxylic acid metalsalts, isocyanates, aldehydes, epoxides, acid chlorides and sulphonylchlorides. Examples of amine-reactive compounds having at least one freeradical polymerizable group include, but are not limited to, acrylicacid, methacrylic acid, 2-carboxyethyl acrylate,2-carboxyethylmethacrylate, methacrylic anhydride, acrylic anhydride,acryloyl chloride, methacryloyl chloride, undecylenic acid,methacryloylisocyanate, 2-(methacryloyloxy)ethyl acetoacetate,undecylenic aldehyde, dodecyl succinic anhydride, glycidyl acrylate andglycidyl methacrylate.

In some embodiments, it is contemplated that the amine-reactive compoundmay be an organosilane or organopolysiloxane oligomers bearing one ormore amine-reactive groups and at least one free radical polymerizablegroup. Examples include, but are not limited to, silanes and oligomericorganopolysiloxanes bearing both an acrylic functional group such asmethacryloxypropyl and amine reactive group such as carboxypropyl,carboxydecyl or glycidoxypropyl. Routes to synthesizing such compoundsby functionalization of the corresponding silicon hydride or siliconalkoxide functional silanes or organopolysiloxane oligomers are known toone of skill in the art.

While numerous amine-reactive compounds are contemplated to be usefulwith the provided methods, one of skill in the art will recognize thatthe selection of a specific free radical polymerizable amine-reactivecompound will depend upon, among other things, the nature of theamine-functional silane and the desired reaction product. In someembodiments, the amine-reactive compound may be selected from acrylicacid, methacrylic acid, 2-carboxyethylacrylate,2-carboxyethylmethacrylate, acryloyl chloride, methacryloyl chloride,glycidyl acrylate and glycidyl methacrylate. Good results have beenobtained when the amine-reactive compound used in the provided methodsis selected from acrylic acid, methacrylic acid, and methacryloylchloride.

In optional embodiments, it may also be desirable to react at least oneadditional amine-reactive compound with the amine-functional silane. Forexample, in addition to the amine-reactive compound described above, itmay be desirable to introduce a second amine-reactive compound having atleast one free-radical polymerizable group per molecule to assist incompleting the desired reaction. As another example, it may be desirableto introduce an amine-reactive compound without a free-radicalpolymerizable group to assist in completing the desired reaction.Examples of such optional second amine reactive compounds include, butare not limited to, acetic acid, citric acid, hydrochloric acid, maleicanhydride, dedecyl succinic anhydride, 3-isocyantopropyltriethoxysilane,3-isocyanato propyltrimethoxysilane, and(isocyanatomethyl)methyldimethoxysilane.

Amine-Functional Silane

The provided methods of preparing silicon-containing microstructuredmaterials comprise reacting an amine-reactive compound with one or moreamine-functional hydrolysable silanes having the formula:

(R¹ ₂NR²)_(a)SiR³ _(b)(OR⁴)_(4-(a+b))

wherein a=1, 2, or 3; b=0, 1, 2, or 3; a+b=1, 2, 3, or 4; R¹ isindependently selected from hydrogen, C1-C12 alkyl, halogen-substitutedC1-C12 alkyl, C1-C12 cycloalkyl, aryl, nitrogen-substituted C1-C12alkyl, and aliphatic ring structures which bridge both R¹ units and canbe N-substituted; R² is independently selected from C1-C30 alkyl; R³ isindependently selected from hydrogen, halogen, C1-C12 alkyl,halogen-substituted C1-C12 alkyl, and —OSiR^(3′) ₃, wherein R^(3′) isselected from C1-C12 alkyl, and halogen-substituted C1-C12 alkyl; and R⁴is independently selected from hydrogen, C1-C12 alkyl, andhalogen-substituted C1-C12 alkyl.

Examples of groups represented by R¹ include, but are not limited to,methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,t-butyl, and cyclohexyl groups, and halogenated derivatives thereof. R¹may also be N-(2-aminoethyl), N-(6-aminohexyl), orN-3-(aminopropylenoxy). Additionally two R¹ groups may be bridgedthrough a cyclic ring, which when included with the N can form apyridyl, pyrrole or azole substituent. Examples of groups represented byR² include, but are not limited to, vinyl, allyl, isopropenyl,n-butenyl, sec-butenyl, isobutenyl, and t-butenyl groups, andhalogenated derivatives thereof. Examples of groups represented by R³include, but are not limited to, hydrogen, halogen, methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl groups,trimethylsiloxy, triethylsiloxy, and halogenated derivatives thereof.Examples of groups represented by R⁴ include, but are not limited to,methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, andt-butyl groups, and halogenated derivatives thereof.

The provided silanes comprise at least one “hydrolyzable group,” whichis any group attached to silicon that may undergo a hydrolysis reaction.Suitable groups include, but are not limited to, hydrogen, halogen, andalkoxy groups.

Examples of suitable amine-functional silanes for use in the providedmethods include, but are not limited to, aminomethyltriethoxysilane;aminomethyltrimethoxysilane; 3-aminopropyltriethoxysilane;3-aminopropyltrimethoxysilane; 3-aminopropylmethyldimethoxysilane;3-aminopropylmethyldiethoxysilane; 3-aminopropylethyldimethoxysilane;3-aminopropylethyldiethoxysilane; 3-aminopropyl dimethylmethoxysilane;3-aminopropyldiethylmethoxysilane; 3-aminopropyl dimethylethoxysilane;3-aminopropyldiethylethoxysilane; n-butylaminopropyltrimethoxysilane;4-aminobutyltriethoxysilane; 4-aminebutyltrimethoxysilane;aminophenyltrimethoxysilane; N,N-diethyl-3-aminopropyltrimethoxysilane;N-(2-aminothyl)-3-aminopropyltrimethoxysilane; 3-aminopropyltrimethylsilane, m-aminophenyltrimethoxysilane,p-aminophenyltrimethoxysilane, 11-aminoundecyltriethoxysilane;2-(4-pyridylethyl)triethoxysilane, and3-aminopropyltris(trimethylsiloxy)silane. Further examples of otheramine functional compounds suitable for use in the provided methods canbe found listed between pages 28-35 in the Gelest catalog entitled“Silane Coupling Agents: Coupling Across Boundaries Version 2.0,”appearing under the category of “Amino Functional Silanes,” and includecompounds listed in the sub-categories of monoamine functional silanes(trialkoxy, monoamine functional silanes; water borne, monoaminefunctional silanes; dialkoxy, monoamine functional silanes); diaminefunctional silanes (monoalkoxy, diamine functional silanes; trialkoxy,diamine functional silanes; water borne, diamine functional silanes;dialkoxy, diamine functional silanes); monoalkoxy, triamine functionalsilanes; secondary amine functional silanes; tertiary amine functionalsilanes; quaternary amine functional silanes; dipodal amine functionalsilanes; specialty amine functional silanes; and cyclic azasilanes. Goodresults have been obtained with the use of 3-aminopropyltriethoxysilane,n-butylaminopropyltrimethoxysilane,N,N-diethyl-3-aminopropyltrimethoxysilane, and3-aminopropyltris(trimethylsiloxy)silane.

Optional Solvent

The provided methods of preparing silicon-containing materials comprisereacting an amine-reactive compound with an amine-functional silane toform a reaction product. In some embodiments, the reaction mayoptionally occur in the presence of at least one solvent to form areaction product that is soluble in the optional solvent.

In some embodiments, the solvent may be selected from toluene, xylene,linear siloxanes, cyclosiloxanes, hexamethyldisiloxane,octamethyltrisiloxane, pentamethyltetrasiloxane, ethyl acetate,propylene glycol methyl ether acetate (PGMEA),di(propyleneglycol)dimethyl ether, methylethyl ketone,methylisobutylketone, methylene chloride, tetrahydrofuran, 1,4-dioxane,N-methylpyrollidone, N-methylformamide, dimethylsulfoxane,N,N-dimethylformamide, propylene carbonate, water, and combinationsthereof. Good results have been obtained with the use of toluene,hexamethyldisiloxane, octamethyltrisiloxane, pentamethyltetrasiloxaneand PGMEA.

Organoborane Free-Radical Initiator

The provided methods of preparing silicon-containing microstructuredmaterials comprise reacting a free radical polymerizable amine-reactivecompound with an amine-functional silane to form a reaction product, andreacting said reaction product with an organoborane free-radicalinitiator in the presence of oxygen to form a polymer material that maybe used as a precursor for forming microstructured coatings, films,solids, and powders. In some embodiments, the reaction of theamine-reactive compound with the amine-functional silane occurs in thepresence of an optional solvent, and the polymer material formed uponfurther treatment with the organoborane is dispersed, suspended,dissolved, or partially dissolved in the optional solvent. If anoptional solvent is not used in the provided methods, the polymermaterial formed upon treatment with the organoborane will be either aliquid or solid. However, said liquid or solid may, in some embodiments,need to be dispersed, suspended, dissolved, or partially dissolved in asolvent in order to adequately form the provided coatings.

An organoborane free-radical initiator is capable of generating a freeradical in the presence of oxygen and initiating addition polymerizationand/or crosslinking. In some embodiments, a free radical may begenerated (and polymerization initiated) upon heating of theorganoborane initiator. In some embodiments, merely exposing theorganoborane initiator to oxygen is sufficient to generate a freeradical. In some embodiments, stabilized organoborane compounds, whereinthe organoborane is rendered non-pyrophoric at ambient conditions, maybe used with the provided methods.

In some embodiments, the organoborane free-radical initiator used withthe provided methods may be selected from alkylborane-organonitrogencomplexes that include, but are not limited to,trialkylborane-organonitrogen complexes comprising trialkylboraneshaving the formula BR″₃, wherein R″ represents linear and branchedaliphatic or aromatic hydrocarbon groups containing 1-20 carbon atoms.Examples of suitable trialkylboranes include, but are not limited to,trimethylborane, triethylborane, tri-n-butylborane, tri-n-octylborane,tri-sec-butylborane, tridodecylborane, and phenyldiethylborane. In otherembodiments, an organoborane free-radical initiator may be selected fromorganosilicon-functional borane-organonitrogen complexes, such as thosedisclosed in WO2006073695 A1.

In some embodiments, it is contemplated that the organoboranefree-radical initiator used with the provided methods may be anorganoborane-organonitrogen complex having the formula:

wherein B represents boron and N represents nitrogen; at least one ofR6, R7, and R8 contains one or more silicon atoms with thesilicon-containing group(s) covalently attached to boron; R6, R7, and R8are groups that can be independently selected from hydrogen, acycloalkyl group, a linear or branched alkyl group having 1-12 carbonatoms on the backbone, an alkylaryl group, an organosilane group such asan alkylsilane or an arylsilane group, an organosiloxane group, analkene group capable of functioning as a covalent bridge to anotherboron atom, a divalent organosiloxane group capable of function as acovalent bridge to another boron atom, or halogen substituted homologsthereof; R9, R10, and R11 are groups that yield an amine compound or apolyamine compound capable of complexing with boron and areindependently selected from hydrogen, an alkyl group containing 1-10carbon atoms, a halogen substituted alkyl group containing 1-10 carbonatoms, or an organosilicon functional group; and at least two of the R6,R7, and R8 groups and at least two of the R9, R10, and R11 groups cancombine to form heterocyclic structures, provided that the sum of thenumber of atoms from the two combining groups does not exceed 11.

Examples of suitable organonitrogens for forming anorganoborane-organonitrogen complex include, but are not limited to, 1,3propane diamine; 1,6-hexanediamine; methoxypropylamine; pyridine;isophorone diamine; and silicon-containing amines such as3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,2-(trimethoxysilylethyl)pyridine, aminopropylsilanetriol,3-(m-aminophenoxy)propyltrimethoxysilane,3-aminopropyldiisopropylmethoxysilane, aminophenyltrimethoxysilane,3-aminopropyltris(methoxyethoxethoxy)silane,N-(2-aminoethyl)-3-aminopropyltrimethoxysilane,N-(6-aminohexyl)aminomethyltrimethoxysilane,N-(2-aminoethyl)-hI-aminoundecyltrimethoxysilane,(aminoethylaminomethyl)-p-benethyltrimethoxysilane,N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane,N-(2-aminoethyl)-3-aminoisobutylmethyldimethoxysilane, and(3-trimethoxysilylpropyl)diethylene-triamine.

In some embodiments, nitrogen-containing compounds that may be usefulfor forming an organoborane-organonitrogen complexes may be selectedfrom organopolysiloxanes having least one amine functional group.Examples of suitable amine functional groups include, but are notlimited to, 3-aminopropyl, 6-aminohexyl, 11-aminoundecyl,3-(N-allylamino)propyl, N-(2-aminoethyl)-3-aminopropyl,N-(2-aminoethyl)-3-aminoisobutyl, p-aminophenyl, 2-ethylpyridine, and3-propylpyrrole.

Other nitrogen-containing compounds that may be useful for forming theorganoborane-organonitrogen complexes for use as organoboranefree-radical initiators in the provided methods may include, but are notlimited to, N-(3-triethyoxysilylpropyl)-4,5-dihydroimidazole,ureidopropyltriethoxysilane, and organopolysiloxane resins in which atleast one group is an imidazole, amidine, or ureido functional group.

In some embodiments, an organoborane free radical initiator for use inthe provided methods may be a trialkylborane-organonitrogen complexwherein the trialkylborane is selected from triethylborane,tri-n-butylborane, tri-n-octylborane, tri-sec-butylborane, andtridodecylborane. For example, an initiator may be selected fromtriethylborane-propanediamine, triethylborane-butylimidazole,triethylborane-methoxypropylamine, tri-n-butylborane-methoxypropylamine, triethylborane-isophorone diamine,tri-n-butyl borane-isophorone diamine, and triethylborane-aminosilane ortriethylborane-aminosiloxane complexes. Good results have been obtainedwith use of TnBB-MOPA (tri-n-butyl borane complexed with3-methoxypropylamine).

Although organonitrogen-stabilized organoborane compounds areparticularly useful as free radical initiators, one of skill in the artwill understand that other organoborane free radical initiators may beused. Examples may include, but are not limited to, ring stabilizedcompounds (such as 9-BBN), or solvent complexed organoboranes (such astrialkylborane-THF solutions).

In various embodiments, a free radical may be generated, andpolymerization and/or crosslinking is initiated, by exposing theorganoborane free radical initiator to air (or other oxygen source),heat, radiation, or combinations thereof. In the case of thermalactivation, the temperature required to initiate polymerization and/orcrosslinking reactions is dictated by the nature of the organoboranecompound selected as the initiator. For example, if anorganoborane-organonitrogen complex is selected, the binding energy ofthe complex will dictate the necessary temperature required to initiatedissociation of the complex and the reaction. In some embodiments, theorganoborane free radical initiator and the reaction product of thesilane and amine-reactive compound are heated together. In someembodiments, no heat is required to initiate polymerization and/orcrosslinking.

Methods

The provided methods of preparing silicon-containing materials comprisereacting a free radical polymerizable amine-reactive compound with anamine-functional silane. Optionally, the reaction occurs in the presenceof at least one solvent to form a reaction product that is soluble inthe solvent. In various embodiments, a desirable reaction product may beformed when the mole ratio of the amine groups in the silane to theamine-reactive groups in the amine reactive compound is from about 0.5to about 1.5. Accordingly, suitable mole ratios (aminegroups/amine-reactive groups) may be 0.5-0.6, 0.6-0.7, 0.7-0.8, 0.8-0.9,0.9-1.0, 1.0-1.1, 1.1-1.2, 1.2-1.3, 1.3-1.4, 1.4-1.5, and all pointstherein. Good results have been obtained when the mole ratio is from 1.0to 1.5. The reaction product may be, but is not required to be, anamine-carboxylate salt or amide bridged complex. Regardless the natureof the reaction product, the provided methods allow for its formation inthe absence of a surfactant or block copolymer, which is in contrast toconventional sol-gel methods.

The provided methods further comprise reacting the reaction product withan organoborane free-radical initiator to form a polymer preparationthat can be used to prepare one or more of the provided coatings,solids, powders. Free radical generation requires oxygen, which may bepresent in the ambient air, dissolved in the precursor and/ororganoborane compositions, or delivered from another oxygen source. Insome embodiments, limiting the concentration of oxygen (but notprecluding it from the system) such as by the use of a nitrogen sweep orpurge may be advantageous for safety (reduced flammability of volatilefluids), for reaction efficiency, or both. In some embodiments, thepolymer preparation formed after treatment with the organoboraneinitiator may be applied to at least one substrate surface and dried toform a silicon-containing coating. In some embodiments, the coatingformed comprises microstructures that are responsive to one or morestimuli. Application of the polymer preparation to the substrate surfacemay be achieved by various techniques, including but not limited to,vapor deposition, liquid deposition, dip coating, flow coating, curtaincoating, spin-on application, spray-on application, and roll-onapplication techniques. In some embodiments, the substrate is asacrificial substrate and the provided methods allow for formation of afree-standing film.

In some embodiments, the silicon-containing coatings formed may befurther treated with heat, acid, or both to form oxidized coatings. Forexample, oxidized coatings may be formed by treating asilicon-containing coating with high heat or at least one strong acid.As another example, oxidized coatings may be formed by treating asilicon-containing coating with at least one strong acid and low heat.In some embodiments, preparation of an oxidized coating comprisesheating a provided silicon-containing coating to a temperature of fromabout 400° C. to about 1000° C. Accordingly, suitable temperatures maybe 400° C.-450° C., 450° C.-500° C., 500° C.-550° C., 550° C.-600° C.,600° C.-650° C., 650° C.-700° C., 700° C.-750° C., 750° C.-800° C., 800°C.-850° C., 850° C.-900° C., 900° C.-950° C., 950° C.-1000° C., and allpoints therein. Good results have been obtained by heating to atemperature of from about 500° C. to about 700° C. Good results havealso been obtained by heating to a temperature of from about 550° C. toabout 650° C. In some embodiments, preparation of an oxidized coatingcomprises contacting a provided silicon-containing coating with at leastone acid. Examples of suitable acids include, but are not limited to,strong acids such as hydrochloric (HCl), hydrobromic (HBr), hydroiodic(HI), nitric (HNO₃), perchloric (HClO₄), and sulfuric (H₂SO₄) acids.Good results have been obtained by using HCl.

In alternative embodiments, the polymer preparation formed aftertreatment with the organoborane initiator may be used to prepare anoxidized solid, powder, or combination thereof by directly treating thepolymer preparation (i.e., without forming a coating) with heat, acid,or combinations thereof. In some embodiments, the polymer preparationmay be directly treated with heat, acid, or combinations thereof to forman oxidized solid. For example, the polymer preparation of (II) may bedirectly treated with high heat or at least one strong acid. As anotherexample, the polymer preparation of (II) may be treated with at leastone strong acid and low heat. The oxidized solid formed may begranulated to form an oxidized powder. In alternative embodiments, abulk solid may be formed by treating the polymer preparation of (II)with heat, vacuum, or combinations thereof. The bulk solid formed can befurther treated with acid, heat, or combinations thereof to form anoxidized solid. For example, a bulk solid may be formed by heating thepolymer preparation in the presence of a vacuum and then once formed,treated with high heat or at least one strong acid to form the oxidizedsolid. As another example, the polymer preparation can be heated to forma bulk solid and then once formed, treated with low heat and at leastone strong acid to form the oxidized solid. The oxidized solid formedcan be granulated to form an oxidized powder. Alternatively, an oxidizedpowder can be prepared by granulating a bulk solid and then treating thegranulated solid with acid, heat, or combinations thereof.

Solids and Powders

In various embodiments, provided are bulk solids, oxidized solids, andoxidized powders prepared according to the provided methods. The bulksolids formed are non-porous or semi-porous and comprise surfacemicrostructures, sub-surface microstructures, or both. Saidmicrostructures may be tapered, cylindrical, conical, or have some otherform or shape. The microstructures may also be responsive to one or morestimuli. Examples of stimuli that can illicit a response in the providedbulk solids include, but are not limited to, humidity, pH, andtemperature. In some embodiments, the stimuli-responsive microstructureshave a mean height or length (depending upon whether it is a surfaceprotrusion or a sub-surface structure) of from about 5 to about 8 nm anda mean diameter of from about 0.8 to about 2.3 μm. Accordingly, amicrostructure may have a mean height or length of from 5-5.5 nm, 5.5-6nm, 6-6.5 nm, 6.5-7 nm, 7-7.5 nm, 7.5-8 nm, and all points therein. Amicrostructure may also have a mean diameter of from about 0.8-1.1 μm,1.1-1.4 μm, 1.4-1.7 μm, 1.7-2 μm, 2-2.3 μm, and all points therein.

The provided oxidized solids and powders are porous. Such porous solidsand powders may be one or more of microporous (having a mean porediameter of less than 2 nm), mesoporous (having a mean pore diameter offrom about 2 nm-50 nm), or macroporous (having a mean pore diameter ofgreater than 50 nm). It is contemplated that the oxidized solids andpowders may be substantially microporous or comprise a substantialnumber of micropores. Thus, in some embodiments, the provided poroussolids and powders may have a mean pore diameter selected from <1 nm,1-1.2 nm, 1.2-1.4 nm, 1.4-1.6 nm, 1.6-1.8 nm, 1.8-2 nm, 2-5 nm, 5-10 nm,10-15 nm, 15-20 nm, 20-25 nm, 25-30 nm, 30-35 nm, 35-40 nm, 40-45 nm,45-50 nm, 50-70 nm, 70-90 nm, 90-110 nm, and all points therein. In someembodiments, the provided porous solids and powders may have a mean porediameter greater than 110 nm. For example, it is contemplated that meanpore diameter may be selected from about 110-500 nm, 500-1000 nm (1 μm),1-10 μm, 10-20 μm, 20-30 μm, 30-40 μm, and 40-50 μm.

Coatings

In various embodiments, provided are silicon-containing coatingsprepared according to the provided methods. Said coatings may benon-porous or semi-porous, and in some embodiments, may comprisestimuli-responsive microstructures. Additionally provided are oxidizedcoatings wherein said silicon-containing coatings have been furthertreated (by treatment with heat, acid, or combinations thereof) to formpores of variable size. The porosity of an oxidized coatings may beselectable, based at least in part, upon the nature of the non-porous orsemi-porous silicon-containing coating from which it is derived. Forexample, stimuli-responsive microstructures of a silicon-containingcoating may be controlled by providing a stimulus prior to oxidation,thereby allowing for selectable porosity and pore structure in theoxidized coating. For example, the oxidized coating may be selected tobe microporous.

In some embodiments, provided are silicon-containing coatings comprisingmicrostructures. In some embodiments, such microstructures protrude fromthe coating surface. The microstructures may be tapered, cylindrical,conical, spherical, hemispherical or have some other form or shape. Insome embodiments, the microstructures are responsive to one or morestimuli. Examples of stimuli that can illicit a response in the providedcoatings include, but are not limited to, humidity, pH, and temperature.In some embodiments, the stimuli-responsive microstructures areprotrusions having a mean height above the surface plane of from about 5to about 8 nm and a mean diameter of from about 0.8 to about 2.3 μm.Accordingly, a protrusion may have a mean height of from 5-5.5 nm, 5.5-6nm, 6-6.5 nm, 6.5-7 nm, 7-7.5 nm, 7.5-8 nm, and all points therein. Aprotrusion may also have a mean diameter of from about 0.8-1.1 μm,1.1-1.4 μm, 1.4-1.7 μm, 1.7-2 μm, 2-2.3 μm, and all points therein.

In some embodiments, the silicon-containing coatings comprisingstimuli-responsive microstructures respond to one or more stimuli byincreasing surface roughness, decreasing surface roughness, changingmicrostructure or morphology, and combinations thereof. For example,microstructure shape may change in response to the one or more stimuli.As another example, microstructures may change from cylindricalprotrusions to lamellar structures in response to the one or morestimuli. In some embodiments, properties of stimuli-responsive coatingsprepared according to the provided methods may be selectively modifiedto provide desired characteristics. For example, one or more ofadhesion, release, reflectivity, and friction may be selectivelymodified to meet the properties desired for an intended application. Itis contemplated that coatings comprising such responsive microstructuresmay be used in a variety of applications.

In some embodiments, also provided are porous oxidized coatings preparedaccording to the provided methods. Such oxidized coatings may beselectively modified to provide desired characteristics, wherein suchcharacteristics will be dependent, at least in part, upon the nature ofthe non-porous or semi-porous silicon-containing coating that is treatedwith heat, acid, or combinations thereof to form the oxidized coating.In some embodiments, the provided porous oxidized coatings may be one ormore of microporous, mesoporous, or macroporous. It is contemplated thatthe oxidized coatings may be substantially microporous or comprise asubstantial number of micropores. For example, a porous oxidized coatingprepared according to the provided methods may have a mean pore diameterof less than 5 nm. Accordingly, such a coating may have a mean porediameter of from 0-1 nm, 1-2 nm, 2-3 nm, 3-4 nm, 4-5 nm, and all pointstherein. It is contemplated that porous oxidized coatings preparedaccording to the provided methods may be used in a variety ofapplications.

In some embodiments, the provided non-porous or semi-porous coatings arefilms. Such films may be stand-alone films or substrate-bound films.Numerous methods of forming stand-alone and substrate-bound films areknown. Substrate-bound non-porous or semi-porous films may be formed byapplication of the polymer preparation (or a dispersion thereof) to atleast one surface of a substrate to form a film (if necessary, allowingthe polymer preparation to dry). Stand-alone non-porous or semi-porousfilms may be formed by application of the polymer preparation to asurface of a sacrificial substrate and removing said substrate afterformation of the film. In some embodiments, the provided stand-alonefilms or substrate-bound films comprise stimuli-responsivemicrostructures.

In some embodiments, the provided oxidized coatings are porous films.Such films may be stand-alone films or substrate-bound films. Numerousmethods of forming stand-alone and substrate-bound films are known.Substrate-bound oxidized films may be formed by application of thepolymer preparation (or a dispersion thereof) to at least one surface ofa substrate to form a non-porous or semi-porous film (if necessary,allowing the polymer preparation to dry); then treating said film withheat, acid, or a combination thereof to form the oxidized film.Stand-alone oxidized films may be formed by application of the polymerpreparation to at least one surface of a sacrificial substrate to form anon-porous or semi-porous film; treating said film with heat, acid, or acombination thereof to form the oxidized film; and mechanically removingsaid substrate after formation of the film. Alternatively, stand-aloneoxidized films may be formed by application of the polymer preparationto at least one surface of a sacrificial substrate to form a non-porousor semi-porous film; treating said film with heat, acid, or acombination thereof to form the oxidized film; wherein said substrate isremoved by the heat, acid, or combination thereof. Alternatively,stand-alone porous oxidized films may be formed by application of thepolymer preparation to at least one surface of a sacrificial substrateto form a non-porous or semi-porous film; mechanically removing saidsubstrate after formation of the film; and treating said stand-alonenon-porous or semi-porous film with heat, acid, or a combination thereofto form the oxidized film.

Substrates

In various embodiments, provided are the coated substrates preparedaccording to the provided methods, wherein said substrates comprise: (i)at least one silicon-containing coating on at least one substratesurface; (ii) at least one silicon-containing on at least one substratesurface wherein the coating comprises stimuli-responsivemicrostructures; (iii) at least one oxidized coating on at least onesubstrate surface, or (iv) combinations thereof. In some embodiments,such the coatings on the provided substrates are films. In someembodiments, such substrates are sacrificial substrates used to formstand-alone films.

In some embodiments, provided are coated substrates comprising at leastone non-porous or semi-porous silicon-containing coating comprisingmicrostructures that protrude from the coating surface and areresponsive to one or more stimuli. It is contemplated that substratescomprising such responsive coatings may be used in a variety ofapplications.

In some embodiments, provided are coated substrates comprising at leastone oxidized coating that is porous, the properties of said coatingdependent, at least in part, upon the nature of the non-porous orsemi-porous silicon-containing coating from which it was derived. Forexample, pore size can, at least in part, be dependent upon by thenature of the non-porous or semi-porous silicon-containing coating. Itis contemplated that substrates comprising such porous oxidized coatingsmay be used in a variety of applications.

EXAMPLES

The present invention will be better understood by reference to thefollowing examples which are offered by way of illustration and whichone of skill in the art will recognize are not meant to be limiting.

Example 1

In a glass vial, 4.01 g of a 50% solution of3-aminopropyltriethoxysilane (Dow Corning) in PGMEA (propylene glycolmethyl ether acetate; Aldrich) was mixed with 1.56 g of a 50% solutionof methacrylic acid (Aldrich) in PGMEA. In a glass vial, 4.01 g of themixture was mixed with 0.16 g of an organoborane initiator, TnBB-MOPA(tri-n-butyl borane complexed with 1.3 molar equivalents of3-methoxypropylamine), to form a free radical-polymerized precursormaterial. The resulting precursor material was filtered through a 0.2 μmfilter then spin coated onto a silicon wafer at 3300 rpm to form acontinuous coating or film, except for a few pinhole defects.

When examined using atomic force microscopy (AFM) in tapping mode, thesample surfaces unexpectedly revealed an array of vertically aligned,fairly uniform cylindrical protrusions ranging from roughly 5 to 8 nm inheight and 0.8 to 2.3 μm in diameter on a molecularly smooth background(root mean square roughness of 0.7 nm) as pictured in FIG. 2.

In contrast to the above methods, when only the3-aminopropyltriethoxysilane/methacrylic acid mixture (i.e., withoutTnBB-MOPA) was spin-coated (after filtering through a 0.2 μm syringefilter) onto a silicon wafer at 3300 rpm for 30 seconds, the resultingfilm was unstable, undergoing rapid dewetting and leaving no continuousfilm. Thus, it was concluded that an organoborane initiator is necessaryfor preparation of the provided coatings and films.

Example 2

A portion of the thin coating/film sample supported on the silicon waferin Example 1 was placed in a forced air convection oven for 2 hours at250° C. The resulting coating/film was characterized by AFM and revealedpores in the approximate locations where the cylindrical protrusionswere present (FIG. 3A).

Example 3

A portion of the thin coating/film sample supported on the silicon waferin Example 1 was placed in a high temperature oven for 2 hours at 500°C. The resulting coating/film was characterized by AFM and revealedcircular depressions or pores in the approximate locations where thecylindrical microstructures were present in Example 1 (FIG. 3B-C).

Example 4

In a glass vial, 2.01 g of a 50% solution of3-aminopropyltriethoxysilane (Dow Corning) in PGMEA was mixed with 0.65g of a 50% solution of acrylic acid (Aldrich) in PGMEA. Next, 1.64 g ofthe mixture was mixed in another glass vial with 0.099 g of TnBB-MOPA toform a free radical-polymerized precursor material. The resultingprecursor polymeric material was filtered through a 0.2 μm filter thenspin coated onto a silicon wafer at 3300 rpm for 30 s to form acontinuous coating/film that had root mean square roughness of 1.4 nm byAFM, as shown in FIG. 4A.

Example 5

The silicon supported thin coating/film sample from Example 4 wassubjected to 250° C. for 2 hours in a forced air convection oven. Whenexamined by AFM, the resulting coating/film had vertically orientedmicrostructures with spherical surfaces. Examined over a larger width in3-D mode, the vertical microstructures showed an aligned mesoporousassembly perpendicular to the surface as shown in FIG. 4B.

Example 6

The silicon supported thin coating/film sample from Example 4 wassubjected to 500° C. for 2 hours in a high temperature oven. Whenexamined by AFM, the resulting coating/film had vertically orientedmicrostructures with spherical surfaces. Examined over a larger width in3-D mode, the vertical microstructures show an aligned mesoporousassembly perpendicular to the surface as shown in FIG. 4C.

Example 7

The coating/film of Example 4 was tested after several weeks of ambientaging then placed in a humidity chamber that was fabricated from a 6cm-tall jar filled approximately ¾ full with deionized water, and toppedwith an upside-down beaker. The coating/film sample was placed at thebase of this chamber and exposed to the humid environment for a periodof time. It was then removed, imaged by AFM, and replaced for anadditional period of time. This cycle was repeated up to a totalexposure time of 45 minutes. In this series of experiments, no attemptwas made to return to the same area during subsequent imaging steps.

The microstructures of the coating/film were observed to expand withtime of exposure to humidity and ultimately change from cylindricalmicrostructures into worm-like lamellar features after 45 minutes, asseen in FIG. 5. The coating/film roughness and height were measured inin-situ experiments and plotted, showing a controllable monotonic growthin microstructure sizes with time of exposure (FIG. 6).

This experiment demonstrates that the provided methods result insilicon-containing coatings and films that can exhibit a strong responseto humidity, and that the microstructure of a given coating/film can becontrolled simply by exposure time to humidity.

Example 8

In a glass vial, an equimolar mixture of 3-aminopropyltriethoxysilane(Dow Corning) and methacrylic acid (Aldrich) was prepared by mixing12.06 g of 3-aminopropyltriethoxysilane and 4.69 g methacrylic acid witha dry nitrogen purge. The exotherm was controlled by placing the vial ina beaker of cool water to prevent excessive heating of the mixture. To5.11 g of this mixture in a weighing dish was added 0.20 g of TnBB-MOPAand stirred with a magnetic stirrer. The sample polymerized within a fewminutes into a clear gel. The material was transferred to a N₂-purgeddry box to complete polymerization.

1.13 g of the polymerized material was transferred into a glass jar andplaced in a 500° C. furnace for 2 hours before the furnace was turnedoff and allowed to return to room temperature overnight. The resultingsolid was tested by nitrogen adsorption studies using a QuantachromAutosorb 1 surface area analysis apparatus and exhibited a Type Iisotherm with results shown in Table 1.

Example 9

72.136 g of an equimolar mixture of 3-aminopropyltriethoxysilane andmethacrylic acid (Aldrich) made using water-jacketed glass reactor wascombined with 2.864 g TnBB-MOPA and mixed in a mixing cup using aHauschild centrifugal mixer for 30 s, followed by two intermittent 45 smixing cycles. The material was transferred to a N₂-purged dry box andallowed to polymerize into a clear gel. The resulting product wastransferred to a ceramic crucible and placed in a 600° C. furnace for 7hours before the furnace was turned off and allowed to return to roomtemperature overnight. The resulting powder was tested by nitrogenadsorption studies using a Micromeritics ASAP 2020 model surface areaanalyzer. The resulting N₂ adsorption results are shown in FIG. 7 andTable 1.

TABLE 1 Nitrogen adsorption data for Examples 8 and 9 Surface t-plott-plot Isotherm Type Pore area micropore external area (IUPAC sizeExample (m2/g) area (m2/g) (m2/g) Classification) (nm) 8 408 395 80 TypeI <2.0 9 418 335 83 Type I 1.0

The nitrogen adsorption isotherms from Examples 8 and 9 exhibit Type Ibehavior (IUPAC classification) which is characteristic of microporoussolids, as shown in FIG. 7. These results demonstrate that the pyrolysisproduct of the method of this invention gives rise to a very fineinternal pore structure (microporous or microporous with partialmesoporosity) that is very different from common silicas and materialsderived from conventional sol-gel techniques.

Example 10

In a glass vial, an equimolar mixture of3-aminopropyltris(trimethylsiloxy)silane (Gelest) and methacrylic acid(Aldrich) was prepared dropwise addition of 2.2 g of methacrylic acid to9.2 g of 3-aminopropyltris(trimethylsiloxy)silane with a dry nitrogenpurge. The exotherm was controlled by placing the vial in an ice bath toprevent excessive heating of the mixture. The mixture formed a solublesolid that was made into a 20 wt % solution in anhydrous toluene.

Example 11

To 2.0 g of the 20 wt % toluene solution of Example 10 was added 0.1 gof TnBB-MOPA. The headspace was purged with dry nitrogen for a fewseconds before capping lightly to allow reaction. The reaction mixtureremained clear and continued to thicken in viscosity over the next 6hours. The resulting solution was coated onto a glass slide using a 5mil doctor blade, and the solvent was evaporated with a heat gun leavingbehind a transparent solid film. A drop of water placed on the filmformed a significantly higher contact angle than on the glass slide.

Example 12

To 2.0 g of the 20 wt % toluene solution of Example 10 was added 0.023 gof glacial acetic acid and swirled lightly to mix. To this solution wasadded 0.1 g of TnBB-MOPA. The headspace was purged with dry nitrogen fora few seconds before capping lightly to allow reaction. The reactionmixture remained immediately thickened and eventually formed atranslucent solution. The solution was coated onto a glass slide using a5 mil doctor blade, and the solvent was evaporated with a heat gunleaving behind a solid film. A drop of water placed on the film formed asignificantly higher contact angle than on the glass slide. After about2 minutes of contact, the water droplet was removed from the surface andleft behind a visibly swollen, whitened imprint within the contact areaindicating a response to the water.

Example 13

In a glass vial, an equimolar mixture of 3-aminopropyltriethoxysilaneand methacryloyl chloride (Alfa Aesar) was prepared by controlledaddition of 1.8 g of methacryloyl chloride to 3.9 g of3-aminopropyltriethoxysilane to form a stable viscous amber coloredclear liquid product.

Example 14

To 1.0 g of the reaction product of Example 13 was added 0.05 gTnBB-MOPA in a glass vial. Upon mixing, a heat rise could be detectedthrough the vial wall, indicating initiation of polymerization. The neatreaction product was a clear, amber colored solid.

Example 15

To 1.4 g of the reaction product of Example 13 was added 1.4 g ofanhydrous toluene to form a clear solution. To 2.6 g of this solutionwas added 0.1 g of TnBB_MOPA. The resulting solution was spin coatedonto a silicon wafer at 3300 rpm for 30 seconds to form a continuouscoating. The film was placed in a nitrogen purged dry box. Upon exposureof a small area of the film to a high humidity air stream (over 90%relative humidity), the exposed area responded by taking on a hazyappearance that was distinct from the unexposed surrounding area. When acontrol untreated silicon wafer was exposed to the same humid airstream, the haze disappeared rapidly upon removal to ambient air. Incontrast, the exposed area of the film of this example retained the hazefor a prolonged period after returning to ambient air.

Example 16

To 2.0 g of the reaction product of Example 13 was added 5.3 g ofanhydrous toluene to form a clear solution. To 2.5 g of this solutionwas added 0.1 g of TnBB_MOPA. The resulting solution was spin coatedonto a silicon wafer at 3300 rpm for 30 seconds to form a continuouscoating. The resulting film was then exposed to vapors of glacial aceticacid by suspending the substrate over the surface of a container ofglacial acetic acid in a nitrogen purged dry box. The resulting filmspontaneously developed a pattern. The film was left in the nitrogenpurged drybox overnight. The resulting surface was resistant to wipingby a laboratory wipe and under an optical microscope was revealed to becomprised substantially of an array of solid hemispherical microdropletsranging from approximately 50-100 μm in diameter.

The present invention should not be considered limited to the specificexamples described herein, but rather should be understood to cover allaspects of the invention. Various modifications and equivalentprocesses, as well as numerous structures and devices, to which thepresent invention may be applicable will be readily apparent to those ofskill in the art. Those skilled in the art will understand that variouschanges may be made without departing from the scope of the invention,which is not to be considered limited to what is described in thespecification.

1. A method of preparing silicon-containing materials, comprising: (I)reacting an amine-reactive compound having at least one free-radicalpolymerizable group per molecule with a silane to form a reactionproduct, the silane having the formula:(R¹ ₂NR²)_(a)SiR³ _(b)(OR⁴)_(4-(a+b)) wherein a=1, 2, or 3; b=0, 1, 2,or 3; a+b=1, 2, 3, or 4; each R¹ is independently selected fromhydrogen, C1-C12 alkyl, halogen-substituted C1-C12 alkyl, C1-C12cycloalkyl, aryl, nitrogen-substituted C1-C12 alkyl, and aliphatic ringstructures which bridge the R¹ units, wherein the aliphatic ringstructures are optionally N substituted; each R² is independentlyselected from C1-C30 alkyl; each R³ is independently selected fromhydrogen, halogen, C1-C12 alkyl, halogen-substituted C1-C12 alkyl, and—OSiR^(3′) ₃, wherein R^(3′) is selected from C1-C12 alkyl andhalogen-substituted C1-C12 alkyl; and each R⁴ is independently selectedfrom hydrogen, C1-C12 alkyl, and halogen-substituted C1-C12 alkyl;wherein a mole ratio of amine groups on the silane to amine-reactivegroups on the amine-reactive compound is from 0.5 to 1.5; wherein thereaction may optionally occur in the presence of at least one optionalsolvent to form a reaction product that is soluble in the at least oneoptional solvent; and (II) reacting the reaction product of (I) with anorganoborane free-radical initiator in the presence of oxygen to form apolymer preparation, wherein the polymer preparation of (II) is selectedfrom (a) a solid; (b) a liquid; or if the reaction of (I) occurs in thepresence of the at least one optional solvent, (c) a dispersion.
 2. Amethod according to claim 1, further comprising forming asilicon-containing coating by (a) contacting at least one substratesurface with a polymer preparation of (II); or (b) contacting at leastone substrate surface with a polymer preparation of (II) dispersed in atleast one solvent.
 3. (canceled)
 4. A method according to claim 2,further comprising forming an oxidized coating by (a) heating thesilicon-containing coating; (b) contacting the silicon-containingcoating with at least one acid; or (c) combinations thereof.
 5. A methodaccording to claim 4, wherein the oxidized coating is porous orsubstantially microporous.
 6. (canceled)
 7. A method according to claim4, wherein the silicon-containing coating is heated to a temperature offrom about 400° C. to about 1000° C.
 8. A method according to claim 1,further comprising forming a bulk solid by heating a polymer preparationof (II), optionally under vacuum.
 9. (canceled)
 10. A method accordingto claim 1, further comprising forming an oxidized solid by (a) heatinga polymer preparation of (II); (b) contacting a polymer preparation of(II) with at least one acid; or (c) combinations thereof.
 11. A methodaccording to claim 10, wherein the oxidized solid is porous orsubstantially microporous.
 12. (canceled)
 13. A method according toclaim 8, further comprising forming an oxidized solid by (a) heating abulk solid; (b) contacting a bulk solid with at least one acid; or (c)combinations thereof.
 14. A method according to claim 13, wherein theoxidized solid is porous or substantially microporous.
 15. (canceled)16. A method according to claim 8, further comprising forming anoxidized powder by granulating a bulk solid to form a powder and (a)heating the powder formed, (b) contacting the powder formed with atleast one acid, or (c) combinations thereof.
 17. A method according toclaim 1, wherein the reaction of (I) occurs in the presence of at leastone solvent selected from toluene, xylene, linear siloxanes,cyclosiloxanes, hexamethyldisiloxane, octamethyltrisiloxane,pentamethyltetrasiloxane, ethyl acetate, propylene glycol methyl etheracetate, di(propyleneglycol)dimethyl ether, methylethyl ketone,methylisobutylketone, methylene chloride, tetrahydrofuran, 1,4-dioxane,N-methyl pyrollidone, N-methylformamide, dimethylsulfoxane,N,N-dimethylformamide, propylene carbonate, water, and any combinationthereof.
 18. A method according to claim 1, wherein the amine-reactivecompound is selected from acrylic acid, methacrylic acid,2-carboxyethylacrylate, 2-carboxyethylmethacrylate, acryloyl chloride,methacryloyl chloride, glycidyl acrylate, glycidyl methacrylate, and anycombination thereof.
 19. A method according to claim 1, wherein thesilane is selected from aminomethyltriethoxysilane;aminomethyltrimethoxysilane; 3-aminopropyltriethoxysilane;3-aminopropyltrimethoxysilane; 3-aminopropylmethyldimethoxysilane;3-aminopropylmethyldiethoxysilane; 3-aminopropylethyldimethoxysilane;3-aminopropylethyldiethoxysilane; 3-aminopropyl dimethylmethoxysilane;3-aminopropyldiethylmethoxysilane; 3-aminopropyl dimethylethoxysilane;3-aminopropyldiethylethoxysilane; n-butylaminopropyltrimethoxysilane;4-aminobutyltriethoxysilane; 4-aminebutyltrimethoxysilane;aminophenyltrimethoxysilane; N,N-diethyl-3-aminopropyltrimethoxysilane;N-(2-aminothyl)-3-aminopropyltrimethoxysilane; 3-aminopropyltrimethylsilane, m-aminophenyltrimethoxysilane,p-aminophenyltrimethoxysilane, 11-aminoundecyltriethoxysilane;2-(4-pyridylethyl)triethoxysilane,3-aminopropyltris(trimethylsiloxy)silane, and any combination thereof.20. A method according to claim 1, wherein the organoborane free-radicalinitiator is a trialkylborane-organonitrogen complex selected fromtriethylborane-propanediamine, triethylborane-butylimidazole,triethylborane-methoxypropylamine, tri-n-butylborane-methoxypropylamine, triethylborane-isophorone diamine,tri-n-butyl borane-isophorone diamine, triethylborane-aminosilanes,triethylborane-aminosiloxanes, and any combination thereof.
 21. Asilicon-containing coating prepared according to the method of claim 2,or a silicon-containing coating prepared according to the method ofclaim 2, further comprising microstructures that are responsive to oneor more stimuli.
 22. (canceled)
 23. An oxidized coating preparedaccording to the method of claim
 4. 24. A bulk solid prepared accordingto the method of claim 8, comprising microstructures that are responsiveto one or more stimuli.
 25. A coated substrate comprising a substratewith at least one surface and the silicon-containing coating of claim 21on at least one substrate surface.
 26. A coated substrate comprising asubstrate with at least one surface and the oxidized coating of claim 23on at least one substrate surface.